Foliage Type and Deprivation Alters the Movement Behavior of Late Instar European Gypsy Moth Lymantria dispar (Lepidoptera: Erebidae)

Abstract

The movement behavior of insects characterizes their ability to disperse, establish, compete, forage, seek mates, and ultimately reproduce. Understanding the movement of invasive insects is particularly important for developing management policies. We conducted laboratory experiments in Minnesota, USA to determine how host type and food deprivation affected the movement of late instars of the European gypsy moth Lymantria dispar (Lepidoptera: Erebidae), an invasive forest insect in North America. Gypsy moth larvae can feed on over 300 species of trees and shrubs. During outbreaks food availability to conspecifics can become severely restricted as developing instars consume increasing amounts of foliage. Larvae were raised on one of five foods: Quercus macrocarpa, Larix laricina, Acer platanoides, Acer saccharinum, or artificial diet. Subsets of fifth and sixth instar larvae were also deprived of food for zero, 24, or 48 h. After the food deprivation period, late instar larvae were placed on a servosphere and their movement paths were recorded. Larvae raised on Q. macrocarpa, a preferred host, were unlikely to move unless starved. They moved farther the longer they were starved. In contrast, when larvae were raised on less preferred hosts, they were more likely to move without prior starvation. These results suggest that feeding on optimal hosts provides gypsy moth larvae with the energy and nutritional requirements to move more quickly to more food when there is none immediately available.

Climate‐related variation of metabolic rate across the distribution of a broadly tolerant invasive forest pest

“…However, this seems unlikely in this system given that L. d. dispar are generally not food limited except during outbreaks (Wittman & Aukema, 2019) and the water content of leaves is relatively high (45%-75%) (Scriber & Slansky, 1981). A more plausible explanation is that larger body size leads to more efficient energy use.…”

“…One common explanation for latitudinal or climate‐related body size clines in insects is that they arise from varying levels of stress resistance to starvation or desiccation (Chown & Gaston, 1999; Cushman et al., 1993). However, this seems unlikely in this system given that L. d. dispar are generally not food limited except during outbreaks (Wittman & Aukema, 2019) and the water content of leaves is relatively high (45%–75%) (Scriber & Slansky, 1981). A more plausible explanation is that larger body size leads to more efficient energy use.…”

Infestation of Early- and Late-Flushing Trees by Spring Caterpillars: An Associational Effect of Neighbouring Trees

“…There are plenty of abiotic and biotic stimuli inducing caterpillars to leave their feeding places (e.g., low quality or lack of food, a contact with a predator or parasitoid, physical stimuli caused by weather conditions, etc.) [4,60,61,94,[120][121][122][123][124][125][126]. Many caterpillars can be seen as they climb tree trunks to get into crowns after rainstorms or strong winds (pers.…”

Suitability of Turkey Oak, European Beech, and Hornbeam to Gypsy Moth Feeding

“…Turkey oak is the most preferred and suitable among oak species in Balkan Peninsula [23] and thus its forests might be common sites where GM outbreaks begin and spread to other forests [24]. After defoliation of optimal oak hosts during outbreak, GM actively searches for available food and may accept less suitable hosts for feeding and oviposition [25][26][27]. For instance, during the last GM outbreak in Serbia, significant amount of beech forests were completely defoliated [28].…”